<template>
  <p>count值为：{{ count }}</p>
  <button @click="add">加n</button>
</template>

<script setup>
import { ref } from 'vue'
const emit = defineEmits(['updateCount'])
const count = ref(1)
const add = () => {
  count.value++
  emit('updateCount', 2)
}
</script>
 